It took me an awful long time, and lots of help from the folks on
#perl6 but in the end, it's done!
It needs a tiny patch to Parrot, but I believe it will be added to the next parrot release. I tried to documented the fixes to the code to help others that might have the same problems.
So now Digest::MD5 for Perl 6 works as good as the Perl 5 one. I'm too tired to say anything else :)